Using mutant cycle analysis to elucidate long-range functional coupling in allosteric receptors

Abstract

Functional coupling of residues that are far apart in space is the quintessential property of allosteric receptors. Data from functional studies of allosteric receptors, such as whole-cell dose-response relations, can be used to determine if mutation to a receptor significantly impacts agonist potency. However, the classification of perturbations as primarily impacting binding or allosteric function is more challenging, often requiring detailed kinetic studies. This protocol describes a simple strategy, derived from mutant cycle analysis, for elucidating long-range functional coupling in allosteric receptors (ELFCAR). Introduction of a gain-of-function reporter mutation, followed by a mutant cycle analysis of the readily measured macroscopic EC50 values can provide insight into the role of many physically distant targets. This new method should find broad application in determining the functional roles of residues in allosteric receptors. © 2012 Springer Science+Business Media, LLC.